Tar spot (Rhytisma salicinum )

• French disease name: Tache goudronneuse à Rhytisma salicinum
• Pathogen name: Rhytisma salicinum (Pers.:Fr.) Fr.
• Kingdom: Fungi
• Phylum: Ascomycota
• Class: Leotiomycetes
• Order: Rhytismatales
• Family: Rhytismataceae
• Partial list of synonyms:
  • Melasmia salicina Lév.

Distribution

• Canada

Damage, symptoms and biology

Black stromata with raised centres 2-5 mm diameter form on upper leaf surfaces.

The major impact of this disease is a reduction in the aesthetic value of ornamentals.

Other information

Raking up and destroying dead leaves in the fall will reduce the severity of the disease.

Canadian Forest Service Publications

Tar spot (Rhytisma salicinum )

Information on host(s)

Main host(s)

• Bebb willow
• Pussy willow
• Willow

Photos

Stromata of Rhytisma salicinum on willow

Eric Allen

Tar spot of willow caused by Rhytisma salicium.